Chelants are often formulated in detergents because of the presence of metal ions, which can be detrimental to end performance. Many highly colored stains incorporate metals. Removal of the metal can often decolorize the stain and/or make it easier to remove by destabilizing its structure. Metal ions can also catalytically decompose bleach in a formulation leading to a significantly reduced performance. Especially transition metal radical ions e.g. Fe, Cu and Mn can accelerate bleach and peroxide decomposition during washing and bleaching. Water hardness ions e.g. Ca and Mg can also cause adverse interaction with surfactants used in washing formulations and lead to a reduction in the effective concentration available. Fatty acids can precipitate as calcium soaps resulting in the formation of soap scum.
Chelants are widely used chemicals that control adverse effects of metal ions in detergent products by chelating the metal. The chelants are often organic compounds, which form multiple bonds with a single metal ion. Chelants can be introduced into the detergent in an acid form or in a salt form; normally the salt form increases the water-solubility of the chelant. However sodium ions will interact with the fatty acids of the detergent composition resulting in the formation of solid soap. Therefore chelants need to be formulated into the composition containing as small amount of sodium ions as possible, nevertheless maintaining the solubility of the chelants. Another requirement for the chelants is their solubility. Selected chelants need to be soluble and stay soluble without the requirement of added water into the detergent composition. Additionally chelants need to be stable in solution during the storage.
Phosphate containing chelants have been used widely because of phosphates capability to sequester alkaline earth metals. However, due to legislation in various countries, level of phosphate in detergents needs to be substantially reduced. Alternatively detergent manufacturers are supply more phosphate free detergents. Therefore the detergent composition formulation needs to fulfill the requirements of regulatory requirements in different countries.
When formulating the compact liquid detergent composition the chelant needs to be selected to fulfill the criteria to control the metal ions, be soluble in the detergent composition, be stabile during the preparation and storage and fulfill the regulatory requirements.
In addressing these problems, the Applicant has surprisingly found that by combining chelants diethylene triamine pentaacetate (DTPA), in a sodium salt form with S,S-ethylene diamine disuccinic acid (EDDS) in a 2-amminoethanol neutralized form or in sodium salt form, the overall quantity of chelants can be decreased while maintaining good solubility and high activity level. Additionally the quantity of undesired sodium ions brought into the compact liquid detergent composition is reduced and therefore formation of undesired sodium soap is reduced. The compact liquid detergent composition of the present invention also covers wider regulatory requirements and can be used as global formulation.
Chelants are known for incorporation into cleaning compositions. For example, in WO2009/013534 (Innospec Limited) salt of ethylenediamine disuccinic acid (EDDS) is used to stabilize the hydrogen peroxide. In WO2009/013539 (Innospec Limited) magnesium salt of ethylenediamine disuccinic acid (EDDS) is used in detergent composition in water-soluble, non-hydroscopic solid form. In WO2009/013541 (Innospec Limited) a mixture of chelants 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and ethylenediamine disuccinic acid (EDDS) is used in detergent compositions. In EP 1280882 (Procter & Gamble) chelants are used in liquid fabric softening compositions. In WO 01/83668 and WO 02/074893 (both Procter & Gamble) chelants have been used in detergent products.